Documentation update for providers.tfvars

[devarshishah3]

Description

CTS generates providers.tfvar to separate provider credentials. This has been captured in the reference example on github but not updated on consul.io docs under root module

Use Cases

Easy user onboarding with CTS and help them understand how provider credentials are secured

Alternative Solutions

A clear and concise description of any alternative solutions, workarounds, or features you've considered.

Additional context

Any other context or screenshots about the feature request.